155 



81. Lichomolgus marginatus, Thorell. 



(PI. LXXXV). 

 l.ichomolgns marginatus, Thorell, 1. o., p. 71, PI. XII: 18. 



Specific Characters. Female. General form of body somewhat re- 

 sembling that of L. albens, the cephalic segment being considerably expanded 

 and much broader than the succeeding ones. No trace however of any sub- 

 division of this segment is to be detected. Tail rather slender, though not 

 fully attaining the length of the anterior division; genital segment sub-fusiform 

 in shape, being slightly dilated in the middle, with no sharp demarcation between 

 the anterior and posterior parts; anal segment somewhat exceeding in length 

 the 2 preceding segments combined, and considerably longer than it is broad. 

 Caudal rami slender and narrow, attaining about half the length of the remainder 

 of the tail, and only slightly divergent, tapering gradually to an obtuse 

 point, each of them having in front of the middle a very delicate bristle 

 arising from the dorsal face; apical setae extremely small and rudimentary, 

 almost obsolete. Anterior antennae of moderate length, and on the whole 

 agreeing in structure with those in L. forficula. Posterior antennae also rather 

 similar, though somewhat more elongated; apical claws longer and thinner, the 

 anterior one, as in that species, fully twice as long as the posterior. Maxillae 

 with the terminal lappet less abruptly bent at the base, and having the mar- 

 ginal cilia shorter and more densely crowded; palp very small with only 2 

 setae on the tip. Maxillipeds scarcely differing in structure from those in 

 L. forficula. Natatory legs also very similar; distal joint of inner ramus in 

 4th pair, however, somewhat less broad. Last pair of legs with the free joint 

 rounded oval in form. Ovisacs large, though extending only slightly beyond 

 the caudal rami. 



Body of the usual whitish colour. 



Length of adult female 1.30 mm. 



Remarks. The present species somewhat resembles in the general 

 form of the body L. albens, from which it is however at once distinguished 

 by the absence of any dorsal suture on the cephalic segment, as also by the 

 form of the genital segment (in female) and of the caudal rami. In the struc- 

 tural details it evidently comes nearer to L. forficula than to L. albens, as 

 shown by the figures given on the accompanying plate. 



Occurrence. Only a few female specimens of this form have as yet 

 come under my notice. They were selected from a number of specimens of 

 L. forficula, collected at different times and in different localities. I cannot, 



